But I don't understand why it is Trial. If I am a nero 9 user, that update should update my nero 9 essentials and not give me a Trial.

You have an ESSENTIALS Version of nero 9 - the ESSENTIALS version is limited in many points.With the update, you get the chance to test the FULL feature set.As said: If you don't want this, just delete the trial serial. Your applications was already updated.